Spring clip terminals



Oct 3, 1967 R. R. SCOVILLE 3,345,606

SPRING CLIP TERMINALS Filed June 30, 1965 2 Sheets-Sheet 1 FIG. 3.

mil? FIG.'2.

INVENTOR Ray R. Scoville ATTORNEYS Oct. 3, 1967 R. R. SCOVILLE 3,345,605

SPRING CLIP TERMINALS Filed June 50, 1965 2 Sheets-Sheet 2 I? a i- INVENT OR Roy R. ScoviIl e ATTORNEYS United States Patent 3,345,606 SPRING CLIP TERMINALS Ray R. Scoville, 5083 Commonwealth Ave., La Canada, Calif. 91011 Filed June 30, 1965, Ser. No. 468,390 16 Claims. (Cl. 339-454) The present invention relates to electrical connector structures, and is more particularly concerned with an improved terminal structure adapted to be mounted upon a circuit board and adapted to receive one or more conductors, e.g., component leads. As will appear, the present invention is especially concerned with terminals of this general type, embodying a spring structure associated with mechanical elements providing an external slot which may be selectively opened to permit direct entry of a plurality of conductors from a variety of directions relative to the terminal.

Various terminals have been suggested heretofore which are adapted to receive and interconnect electrical components such as resistors, capacitors, semi-conductor devices, etc. In many instances, these prior terminals have been arranged to retain lead wires from such components by means of solder or like fastening agents. Such solder-type terminals are not readily useful in some environments. For example, in breadboard experimenting work, it is often disired to add or remove components from a terminal; and the relatively permanent types of fastening which are achieved by solder make such component alteration difficult. In addition, when solder is employed, there is always the danger of subjecting various components to excessive heat; and when such danger exists, alternative forms of terminal structures are preferred.

These difficulties and limitations which characterize solder-type terminals have resulted in a demand for socalled solderless terminals; and various forms of such solderless terminals have been suggested heretofore. By way of example, one such terminal is described in my prior Patent No. 3,104,926 issued Sept. 24, 1963 for Solderless Terminal. The terminal there described comprises a U-shaped body member having an elongated slot formed in one wall thereof, with said slot being surrounded by a spring member. Component leads may be attached to the terminal by compressing the spring member, thereby to expose a portion of the aforementioned elongated slot, whereafter said leads can be inserted into the slot. Leads can also be inserted between adjacent convolutions of the spring member through said slot. In general, however, because of the interior nature of the slot provided in said prior terminal, all component leads must be threaded through the terminal slot, and pass through said slot in a single direction. If a plurality of component lead Wires are oriented at different directions relative to the terminal, it is normally necessary to bend or twist the component leads or connector wires into a particular direction corresponding to the slot orientation before the terminal connections can be effected.

Other forms of terminals have been suggested wherein an interior slot, hole, or recess is provided, including some wherein the slot may be laid open by depressing a portion of the terminal against a spring. In general, these other terminals are subject to the same disadvantages, i.e., since the lead receiving slot or recess is interior in nature, and since it is normally adapted to receive leads from particular directions only, lead wires must be twisted or bent into a desired final orientation corresponding to the slot or recess orientation in the terminal.

These prior interior slot solderless terminals have been considered objectionable under some circumstances. It

has been found, for example, that when lead wires approach the terminal from different directions (which is, of course, a normal circumstance), the required bending and twisting of lead wires, needed to conform the wire orientation to the terminal configuration, increases the time necessary to wire up a particular circuit, makes it more difficult to add or remove components from a wired circuit, and, indeed, places undesirable mechanical stresses on various electrical components. In addition, the interior nature of the terminal slots or recesses provided heretofore have placed definite limitations on the number of leads which can be accepted by any particular terminal. In addition, in some cases, the slot configuration has been such that when the slot is opened or exposed to insert a new lead wire therein, there is real danger that a previously inserted wire of lead may fall out of the slot. This too has made the wiring of circuits more difiicult, since it is necessary to manually hold some leads in place when a new lead is being inserted or removed from the terminal.

These mechanical difliculties have, moreover, often been accompanied by electrical problems in that relatively poor electrical contact is achieved in many prior solderless terminals. More particularly, it has been found that in certain spring type solderless terminals suggested in the past, the spring is so arranged that, if leads are inserted into the terminal, the spring pressure tends to be distributed over a relatively large contact area; and the result has been reduced spring pressure adjacent any particular lead, whereby the electrical junction formed may exhibit relatively high resistance. r

The present invention, recognizing these difiiculties of prior solderless terminals, is directed toward the provision of a new and highly improved form of solderless terminal having an external slot arrangement adapted to receive a relatively large plurality of wires or component leads from a variety of different directions, without requiring that the wires or leads be materially bent or twisted when they are inserted into the terminal slot. The parts of my new terminal are, moreover, so arranged that engagement between the terminal and an inserted wire is essentially of a point contact nature, whereby the spring force of the terminal is more highly concentrated at a particular point than has been the case heretofore. The area over which electrical contact is made is thereby reduced, and the spring pressure exerted on the contact area is increased, whereby better electrical connections are achieved.

It is accordingly an object of the present invention to provide an improved solderless terminal adapted to receive and retain component leads approaching the terminal from a variety of different directions without requiring them to be threaded through a hole, and without requiring that said leads be bent or twisted at the time they are inserted into the terminal.

Another object of the present invention resides in the provision of a solderless terminal adapted to receive and retain wires and component leads, and adapted to hold such wires and component leads in place when wires are newly added to or removed from the terminal.

A still further object of the present invention resides in the provision of a solderless terminal characterized by an external slot having one or more knife edge portions arranged to engage a wire or corn-ponent lead in essentially point contact relation, whereby the area of electrical contact is reduced below the area'which has been characteristic of solderless terminals suggested heretofore.

A further object of the present invention resides in 0 the provision of a solderless terminal incorporating a component lead by the terminal is effectively increased above the spring pressure which has been characteristic of terminals suggested heretofore.

A further object of the present invention resides in the provision of a new form of terminal adapted to permit faster and more reliable circuit set ups, without soldering, than has been possible heretofore.

Still another object of the present invention resides in the provision of a new form of terminal adapted to be used in both experimental applications, and in various non-experimental permanent circuits wherein soldering is undersibale.

A further object of the present invention resides in the provision of a solderless terminal which is relatively inexpensive, more reliable in operation, and which exhibits substantially lower contact resistance than has been the case with solderless terminals suggested heretofore.

In providing for the foregoing objects and advantages, the present invention contemplates the provision of an open slot or direct side entry type of solderless spring clip terminal comprising a U-shaped metallic post having an open top provided with fingers adapted to receive and retain a washer-type covering piece. A plunger having spaced tines is fitted into the interior of the U-shaped post below the covering piece; and said covering piece is provided with apertures adapted to slidably receive the tines of said slotted plunger whereby said plunger may be slid up and down within the U-shaped post to cover or uncover an open slot in said plunger formed between the tines thereof. One or more sides of said slot (i.e., one or more edges of the aforementioned tines) are of knife edge or beveled configuration; and the slot itself preferably has a width somewhat greater than the largest diameter of any lead wire to be inserted therein, whereby two or more lead wires can be passed through said slot at right angles to one another.

A helical spring is provided in surrounding relation to a portion of said U-shaped post, and in surrounding relation to and in engagement with a portion of said slotted plunger, in a position tending to urge the plunger and its tines in an upward direction toward the aforementioned covering flat piece. Accordingly, the slot provided between the tines of the plunger can be variably exposed by pressing the plunger downward against the force of the helical spring, thereby to permit lead wires to be inserted or removed from the slot; and, upon release of the plunger, the said spring moves the plunger upward so as to bind the lead wires between the edges of said slot and the flat covering piece. In so binding the lead wires, engagement is normally affected between a knife edge portion of the terminal and said lead wire, whereby the contact area is smaller than has been characteristic of terminals suggested heretofore, and whereby the force of the aforementioned helical spring tends to be concentrated and thereby effectively increased at the contact area.

The aforementioned U-shaped post is preferably provided with a further U-shaped section of smaller diameter, located adjacent the bottom portion of the terminal and adapted to be a press fit into an aperture provided in a mounting base or terminal board. The terminal may, therefore, readily be mounted upon and removed from a mounting base or board. In addition, as will appear, the arrangement adjacent the mounting portion of the terminal is such that the terminal may be readily associated with bus wires or bussing strips, thereby to permit a plurality of terminals to be electrically connected to one another.

The foregoing objects, advantages, construction and operation of the present invention will become more readily apparent from the following description and accompanying drawings, in which:

FIGURE 1 is a perspective view of an improved solderless terminal constructed in accordance with the present invention;

FIGURE 2 is an exploded view of the component parts constituting the terminal of the present invention;

FIGURE 3 is an enlarged diagrammatic top view of a portion of the terminal, taken on line 33 of FIGURE 1, illustrating how component leads may be inserted into the exterior open slot of the present invention;

FIGURE 4 is a perspective view of a circuit board having terminals of the present invention mounted thereon, and associated with various components and lead wires;

FIGURE 5 is a diagrammatic view illustrating how the terminals of the present invention may be associated with a bussing strip;

FIGURE 6 is a side cross-sectional view of a modified form of terminal constructed in accordance with the present invention;

FIGURE 7 is a view taken on line 77 of FIGURE 6;

FIGURE 8 is a cross-sectional view taken on line 88 of FIGURE 6;

FIGURE 9 is a side cross-sectional view of a further modified form of the present invention;

FIGURE 10 is a view similar to FIGURE 9, illustrating how the terminal of FIGURE 9 may be operated in practice;

FIGURE 11 illustrates a cap structure which may be used in conjunction with the terminals of FIGURES 1 through 10 to facilitate opening of the terminal;

FIGURE 12 is a side cross-sectional view of a still further modification of the terminal of the present invention;

FIGURE 13 is a top view of a modified form of covering piece or washer member such as may be employed in the various terminals of FIGURES 1 through 12, inc1u sive; and

FIGURE 14 is a side view of the member shown in FIGURE 13.

Referring now to FIGURES 1, 2 and 3 (and to FIG- URES 6 and 9, which are also pertinent), it will be seen that a solderless terminal constructed in accordance with the present invention may comprise a U-shaped conductive or metallic terminal post 10 having an upper portion 10a and a lower portion 1012 each of generally U-shaped cross-section. The upper portion 10a of post 10 has an outside diameter of approximately 0.125 inch, whereas the lower portion 10b has an outside diameter of approximately 0.082 inch. It will be noted, particularly in the illustration of FIGURES 2 and 3, that the cross-sectional configuration of portions 10a and 101) may actually be almost circular, with the legs of the U having free ends spaced from one another as at 11. In the alternative, as will appear subsequently in reference to FIGURE 8, the cross-sectional configuration may comprise substantially straight legs, again spaced from one another. It should, therefore, be understood that the term U-shaped used in the following description and in the appended claims is intended to refer to various possible cross-sectional configurations constituting a partially closed configuration having spaced free edges defining an open area or slot such as 11. The upper portion 10a of terminal post 10 is, as note-d previously, of larger diameter than the lower portion 10b thereof; and said upper portion is adapted to cooperate with various other elements (to be described) constituting the electrical connector portion of the termi nal, whereas, the lower portion 10b of the terminal post 10 comprises a mechanical supporting structure adapted to be inserted into a complementary aperture in a circuit board or mounting base.

An elongated, flat plunger 12 is slidably disposed within the terminal post 10 in the upper portion 10a thereof. Plunger 12 is formed of metal or other conductive material and includes an uppermost section 12a adapted to act as a finger piece which can be manually engaged to depress the slidable plunger 12 downwardly within post 10. The forward edge 14 of plunger 12 is located closely adjacent the open area or slot 11 of post 10 when said plunger 12 is properly positioned within post and said forward edge 14 of plunger 12 is beveled into a knife edge which protrudes from the open slot 11 to a position slightly forward of the post 10 (see in this respect FIG- URES 3, 6, 8, and 9).

The rear edge of plunger 12 defines an outstanding or transverse protuberance which is adapted to be inserted into an elongated slot 16 formed in the rear surface of post portion 10a opposite to the open area or slot 11 of said post. The forward edge of plunger 12 includes an L-shaped projection comprising a member 17 extending outwardly from, and a further member 18 extending upwardly in a direction substantially parallel to and space from, the knife edge 14 of plunger 12. The inner edge of member 18 is preferably also beveled to form a knife edge 19. It will be appreciated, particularly in reference to FIGURE 3, that the knife edges 14 and 19 need not be extremely sharp, and may actually be of a blunted nature; and the term knife edge used herein, and in the appended claims, is intended to cover all such beveled configurations. The beveled sides of edges 14 and 19 present inclined surface areas which facilitate the positioning of wires or component leads perpendicularly to one another within the terminal thereby to permit maximum angularity between such wires or component leads without bending of the same.

In one typical embodiment of the present invention, the overall height of plunger 12 is approximately 0.67 inch; the height of sections 12a above protuberance 15 is approximately 0.36 inch; the width of plunger 12 and of section 12a is approximately 0.135 inch; and the thickness of plunger 12 in a direction transverse to the axis of post 10 is approximately 0.04 inch.

The members 12a and 18 actually comprise a pair of tines which are spaced from one another by the member 17; and as is best apparent from the exploded representation of FIGURE 2, the members 12a, 17, and 18 cooperate with one another to define a relatively wide U-sha-ped slot which, when plunger 12 is inserted into tube 10, is located exterior of said tube. This exterior slot, formed by members 12a, 17, and 18, is adapted to receive lead wires or conductors (see, for example, FIGURE 3), with said lead wires being adapted to assume mutually perpendicular directions as mentioned above. The dimension of member 17 is preferably so chosen that member 13 is spaced from member 12a by about 1.4 times the diameter of the largest wire to be received in said external open slot so that it may pass through at 45 to the plane of plunger 12; e.g., the spacing between knife edges 14 and 19 may be approximately 0.056 inch. In a typical installation, the largest wire to be received may have a diameter of approximately 0.04 inch.

The uppermost end of post 10 is provided with three fingers or lugs 20, 21 and 22. These lugs 20 through 22 are adapted to be slid through an aperture 23 in a washer member 24 adjacent complementary portions of said aperture 23, as is illustrated in FIGURE 2. The said lugs 20, 21 and 22 may then be bent across the top of washer member 24 to retain said washer member 24 in place across the top of terminal post 10 (see FIGURES l, 6, and 7). The aperture 23 in washer member 24 defines an elongated central portion having a forward arrow-shaped end 25 conforming essentially to the shape of knife edge 14 on plunger 12; and said central portion of aperture 23 further includes a squared rear end 26 adapted to receive lug 21 and also adapted to receive the rear edge of plunger 12. Washer 24 includes a further aperture 27 disposed forwardly of aperture 23, and conforming in cross-sectional shape to the shape of member 18 and its knife edge 19. When plunger 12 is inserted into post 10, the protuberance 15 of said plunger extends through slot 16; the upper section 12a of said plunger extends upwardly through washer 24 adjacent the portions 25 and 26 of aperture 23; and the tine 18 with its knife edge 19 extends through said washer 24 via aperture 27. This assembled 6 configuration of the plunger 12, terminal post 10, and washer 24 is best depicted in FIGURES l, 6 and 9.

It will be appreciated that, by the arrangement thus far described, an exterior slot is definedl between the parts 12a, 17 and 18, and the lower surface of washer 24, when the parts are assembled in the manner described. Since the plunger 12 is adapted to be slidably moved up and down relative to apertures 16, 23, and 27, the. actual size of the slot thus formed exterior to post 10 depends upon the vertical position of plunger 12 relative to washer 24. Normally, the plunger 12 is held in an uppermost position so that this exterior slot is substantially closed. More particularly, the overall terminal structure is associated with a helical metal spring member 30 which is disposed in surrounding relation to portion 10a of post 10. The post 10 is provided with a pair of integral hook members 31, adjacent its forward free edges, and said post 10 is also formed with a protruding dimple 32 adjacent its rear surface. The lowermost edge of helical spring 30 rests upon the upper portions of hook members 31, and upon the upper portion of dimple 32. The uppermost end of said spring 30, when the parts are assembled, bears upon the lower edges of protruding portions 15 and 17 of plunger 12 (see, in this respect, FIGURES 6 and 9).

The arrangement is accordingly such that spring 30 assists in retaining plunger 12 in position within tubular post 10; and said spring 30, moreover, normally exerts an upward force on plunger 12 tending to move the protuberance 15 of said plunger 12 into engagement with the upperost edge of slot 16. At this time, the upper edge of member 17 is closely adjacent to, and may in fact contact, the lower surface of washer 24. When a force is exerted downwardly on plunger 12, the spring 30 will be compressed and the tines 12a and 18 will move downwardly in their associated washer openings. As a result, the external slot will be opened between the lower surface of washer 24 and the parts 12a, 17, and 18, with the size of this slot being dependent upon the extentto which plunger 12 is pushed downwardly. Component leads or other conductor wires can be inserted into this exterior open slot, as is best illustrated in FIGURE 3, whereupon the plunger 12 can be released causing the spring 30 to move the plunger upwardly so as to hold the component leads in place within the closed slot.

Since the component lead receiving slot of the terminal is exterior to the post 10, and since it is dimensioned wider than the diameter of any lead to be inserted therein, leads may be inserted into said slot from a variety of directions without requiring that said leads be bent or twisted. This consideration is illustrated in FIGURE 3 wherein three electrical components 35, 36 and 37 (e.g., resistors, capacitors, transistors, or the like) are shown as being provided with leads 35a, 36a, and 37a, respectively. The leads 35a, 36a, and 37a are shown as crossing one another in the region of the exterior terminal slot. The leads 36a and 37a can in fact cross one another at without requiring anybending or twisting of the leads. Moreover, the leads may extend straight through the slot as is indicated by lead 35a, or can extend through said slot at any convenient angle depending upon the positioning of the component in an overall circuit, all without requiring that the terminal leads be bent or twisted. It will be appreciated, of course, that the terminal leads can, if desired, be bent somewhat; but this is not mandatory with the terminal of the present invention, as was the case with many terminals suggested heretofore.

Any one lead can be inserted at such an angle that it lies substantially along opposed beveled sides of the knife edges 14 and 19. Moreover, since the leads cross one another at substantially point contact regions, very forcible engagement is achieved between the terminal and the several component leads when the plunger 12 is released for upward movement by spring 30. It will further be seen that since the regions of contact between the several leads and the terminal of the present invention are limited in area, the force of spring 30 tends to concentrate in the limited areas, thereby effectively increasing the closure force of the terminal, and reducing contact resistance.

Terminals constructed in accordance with the present invention may be used in conjunction with circuit boards to form any desired circuit configuration. This consideration is shown in FIGURE 4 wherein a circuit board 40 is provided with a plurality of orifices 41. The lower portion 1% of terminals such as 42 through 45 inclusive can be inserted into any desired ones of said orifices 41; and, moreover, said terminals can be oriented in any desired direction within one of said orifices 41. The portion b of any given terminal resiliently engages the board edges defining orifices 41, whereby any given terminal can be relatively easily inserted into and removed from a board orifice as desired. Components may extend between the several terminals 42 through 45 in any desired configuration; and typical such components have been depicted at 46.

The hook members 31 of each terminal form, in conjunction with dimple 32, an abutment defining the extent to which any given terminal can be slid into a board. These hook portions 31, by reason of their configuration, moreover provide a facility for receiving further leads which can be used to interconnect any one terminal to any one or more other terminals. Such leads, which can comprise bus wires, are typified by the lead 47 shown in FIGURE 4; and such a lead can be easily inserted into any desired terminal in the region between the hook members 31 of that terminal, and the lowermost edge of the spring 30 for that terminal.

Other bussing arrangements can be used With the terminal of the present invention; and one alternative form of bus arrangement is shown in FIGURE 5. In this particular arrangement, the board 40a is again provided with apertures 41a adapted to receive terminals such as 42a. The lowermost portion 10b of each such terminal 42a is inserted through a conductive perforated strip 48 which acts as a bussing strip. Any two terminals 42a inserted into spaced apertures of bussing strip 40a will be electrically connected to one another via said bussing strip. In order to reduce the contact resistance between each terminal 42a and the common bussing strip 48, an additional small coil spring 49 can be provided in surrounding relation to the post portion 10b in the region between hook portions 31 and bussing strip 48. In assembling an arrangement of the type shown in FIGURE 5, a bus strip such as 48 may be placed upon the terminal board 40a at any desired position. A small spring member such as 49 can then be inserted onto the mounting post portion 10b of the terminal, whereafter the mounting post portion 10b is inserted through superposed apertures in bussing strip 48 and the underlying board 40a. By pressing the terminal 42a downwardly, the spring 49 will be compressed to achieve good electrical continuity between the terminal 42a and the bussing strip 48.

A slightly modified form of the terminal thus far described is illustrated in FIGURES 6, 7, and 8. For the most part, the terminal elements, their relative dispositions, and their operation conform to the description already given; and, therefore, like numerals have been used for like parts. In order to stress the various configurations which the U-shaped terminal post can take, FIGURE 8 (taken on line 88 of FIGURE 6) shows a cross-sectional configuration 100 for the post which has straight legs. In addition, it will be recalled that in the arrangement of FIGURES 1, 2 and 3, the external open slot provided by the terminal of the present invention had only two opposed knife edges 14 and 19. Actually only one knife edge can be provided, if desired; and, in the alternative, all three edges of the parts 12a, 17 and 18 in post 12 can be provided with knife edges. This latter configuration is depicted in FIGURE 6 by the additional knife edge 50 formed at the upper extremity of member 17. Knife edge 50 improves the electrical contact between the terminal and the lowermost conductor inserted into the terminal slot. Component leads inserted into the open slot defined between knife edges 14, 19 and 50, and the lower surface of washer 24, will, therefore, experience even lower contact resistance than is the case in the arrangement of FIGURES l, 2, and 3.

A still further knife edge may be formed on the lower edge of washer 24 to achieve the lowest possible contact area and the greatest effective spring force in the region of component lead engagement. An alternative form of washer 24 providing this additional knife edge is shown in FIGURES l3 and 14. The washer 24 may be provided with a crimped configuration, as at 51, between the apertures 23 and 27 of said washer; and this crimped configuration affords a small area or linear contact region 52 which faces the exterior open slot defined between knife edges such as 14, 19 and 50 of the terminal. Accordingly, component leads inserted into the terminal slot defined between these several edges will be engaged by knife edge surfaces at both the bottom and top of the exterior terminal slot.

A still further variant of the present invention is shown in FIGURES 9 and 10. It will be appreciated from the description of the terminal thus far given that the plunger 12 must be pushed downwardly against the force of spring 30 and held in this downward position throughout the time that wires are inserted into the open slot defined between the several knife edges discussed previously. Under some circumstances, it may be desirable to keep the slot open for a period of time without requiring that manual force be constantly exerted upon the plunger 12. This is particularly so during the initial stages of circuit fabrication, when an experimenter may desire to place a number of leads into a terminal, and may desire to avoid having to hold the plunger 12 down throughout this period of time. The plunger 12 of the present invention can, by slight modification, be adapted to latch in a downward position, so as to permit this type of operation.

More particularly, the rear edge of the plunger 12 adjacent the finger portion 12a thereof can be provided with a notch 55, the lowermost edge of which is inclined slightly upward as at 56. When the finger portion 12a is depressed downwardly, and if a slight rearward force is simultaneously exerted upon the plunger 12, the portion 56 of notch 55 will enter slot 16 formed at the rear surface of post 10, and will engage the uppermost portion of the slot thereby holding the plunger 12 in a downward position as is illustrated in FIGURE 10. The actual inclination of the plunger 12 has been somewhat exaggerated in FIGURE 10 for purposes of clarity. When the parts are latched in the position shown in FIGURE 10, the slot 57 provided for the reception of component leads will be held in an open position thereby permitting as many leads as is desired to be inserted into said slot. Moreover, it will be noted from the showing in FIGURE 10 that, in its latched position, the tine 18 may be completely removed from its complementary washer orifice 27, with the uppermost nose 18a of tine 18 being spaced below the lower surface of washer 24, whereby some leads can, in fact, be inserted over the nose 18a of tine 18. Upon effecting a slight forward pressure on the finger piece 12a of plunger 12, the plunger 12 will be unlatched, whereupon the spring 30 will close the slot 57 in the manner described previously. In order to assure that the nose 18a of tine 18 does not bind on the under surface of washer 24, during such an unlatching of the plunger 12, it is preferred that, in the embodiment described in reference to FIGURES 9 and 10, the nose of the tine 18 be rounded as illustrated. By such an arrangement, the tine 18 will be guided directly back into its washer orifice 27 when the plunger 12 is released.

In order to facilitate manipulation of the plunger 12, in the several embodiments thus far described, it may also be desirable to provide a snap-on plastic pusher or cap such as is illustrated at 60 in FIGURE 11. The cap 60 may be 9 of simple molded construction and is preferably somewhat flexible so that it is retained on top of plunger 12 by a friction fit. The cap 60 reduces the possibility of an operator hurting his finger due to prolonged manual engagement with a relatively narrow metallic part 12a forming the top of plunger 12.

A still further modification of the invention is shown in FIGURE 12. In this arrangement, the portion 12a of the plunger 12 is made somewhat longer than was the case in the arrangement of FIGURES 1 through and the uppermost portion of this elongated plunger is provided with screw threads such as at 61. A threaded bushing 62, which may have an external knurled configuration, is threaded onto threads 61 above the position of washer 24. Actually, the bushing 62 can have its lowermost edge spaced relatively far from the upper surface of washer 24 under normal circumstances; and the plunger 12 can be provided with a latching recess such as at 55, so that, under normal circumstances, the plunger can be manually pushed downward, latched if desired, and released when desired, all in the manner described in reference to FIG- URE 1 through 10 inclusive. When the bushing 62 is screwed downwardly into engagement with the upper surface of washer 24, a positive mechanical force will be exerted upwardly on the plunger 12 so as to clamp component leads such as 63 within the external terminal slot even more strongly than would be accomplished by the spring alone. Indeed, as much force as is desired can be achieved in this way simply by varying the degree to which bushing 62 is turned downward. The mechanical clamping of which the terminal shown in FIGURE 12 is capable thus achieves electrical connections which are extremely strong and which can be used for permanent circuit configurations. The arrangement of FIGURE 12 thus combines the advantages of a readily manipulable terminal, with the advantages of a substantially permanent connection.

While I have thus described preferred embodiments of the present invention, many variations will be suggested to those skilled in the art and certain of these variations have, in fact, already been described. It must, therefore, be understood that the foregoing description, including the dimensions given, is meant to be illustrative only and should not be considered limitative of my invention. All such variations and modifications as are in accord with the principles described are meant to fall within the scope of the appended claims.

Having thus described my invention, I claim:

1. An electrical terminal comprising a hollow conductive post having an elongated slot in a surface thereof, a conductive plunger slidably disposed within said post, said plunger having a portion extending outwardly through said slot, said plunger including an L-shaped projection comprising a first member extending outwardly of said post from said extending portion of said plunger and a second member extending upwardly from said first memher in a direction generally parallel to said slot at a position spaced outwardly of said post, further conductive projecting means extending outwardly from said post at a fixed position above said first member and extending toward said second member wherein said extending portion, said L-shaped projection and said further projecting means define a variably sized aperture disposed external of said post for receiving electrical conductors, and spring means disposed between said post and said plunger for normally urging said plunger in a direction tending to bring said first member closely adjacent said further projecting means whereby said aperture has a minimum cross-sectional area, said plunger being movable within said post against the force of said spring for moving said L-shaped projection downward relative to said further projecting means thereby to increase the cross-sectional area of said aperture.

2. The terminal of claim 1 wherein said further projecting means comprises a conductive plate having an 10 opening therein adjacent said second member, said second member passing through said opening in said plate during at least part of the range of movement of said plunger.

3. The terminal of claim 2 wherein said plate includes a further opening overlying said hollow post, a portion of said plunger extending upwardly from said hollow post through said further opening to a position above said plate to provide a finger engageable portion for manipulating said plunger.

4. The terminal of claim 1 including cooperating abutment means on both said plunger and said post for selectively latching said lunger against the force of said spring means at a position wherein said aperture has a cross-sectional area greater than said minimum crosssectional area.

5. The terminal of claim 1 wherein said extending portion of said plunger includes a first knife edge facing and extending substantially parallel to said second member, said second member defining a second knife edge facing and extending substantially parallel to said first knife edge.

6. The terminal of claim 5 wherein said first member defines a third knife edge extending between said first and second knife edges.

7. The terminal of claim 5 wherein said further projecting means defines a further knife edge located between said first and second knife edges at a position facing the interior of said variably sized aperture.

8. An electrical terminal comprising a conductive elongated post of substantially U-shaped cross-section having a first elongated slot in the wall portion thereof connecting the legs of said U, the spaced free edges of the legs of said U defining a second elongated slot extending along said post at a position opposite and substantially parallel to said first elongated slot, an elongated conductive plunger slidably positioned within said post, said elongated plunger having transverse first and second conductive projections extending through said first and second slots respectively to positions exterior of said post, said second projection including a further conductive member spaced outwardly of said post and extending transverse to said second projection in a direction substantially parallel to the direction of elongation of said post, and a transverse plate member of conductive material attached to said post at a position spaced from said first and second projections, said conductive plate member having an aperture through which said further conductive member extends wherein transversely disposed conductive surfaces of said second projection, further member, and plate member define a variably sized opening positioned exterior of said post through which electrical conductors may be passed, the size of said variably sized opening varying with variations in the slidable position of said plunger within said post.

9. The terminal of claim 8 including resilient means for normally urging said transverse conductive projections toward said transverse plate member.

10. The terminal of claim 8 including means adjacent one end of said post for attaching said post to a base structure, said plate member being attached to said post adjacent the other end of said post, abutment means on said post between the opposing ends of said post, said transverse first and second projections being located between said abutment means and said plate member, and a coil spring surrounding said post and extending between said abutment means and said transverse first and second projections.

11. The terminal of claim 10 including a further coil spring surrounding said post between said one end thereof and said abutment means for increasing the area of engagement between said post and said base structure.

12. The terminal of claim 10 wherein said abutment means comprise outstanding hook portions adapted to engage a further electrical conductor.

13. An electrical terminal comprising a conductive post, a conductive plunger slidably disposed within said post, said plunger including a conductive projection extending outwardly through a slot in said post, said conductive projection defining a generally U-shaped slot the edges of which are located in a plane passing through the axis of said post, further conductive means extending outwardly from said post at a fixed position adjacent the open side of said U-shaped slot, said further means cooperating with the U-shaped slot in said conductive projection to define a substantially closed, variably sized aperture dis-posed external of said post for receiving electrical conductors, the size of said aperture varying with variations in the position of the conductive projection on said slidable plunger relative to the fixed position of said further conductive means, and resilient means disposed between said post and said plunger for normally urging said plunger in a direction tending to reduce the size of said external aperture toward a minimum cross-sectional area, said plunger being movable relative to said post against the force of said resilient means for increasing the cross-sectional area of said external aperture.

14. The terminal of claim 13 including mechanical means on said terminal for selectively applying a force additional to that of said resilient means tending to reduce the size of said aperture toward said minimum crosssectional area.

15. The terminal of claim 14 wherein said mechanical means comprises a threaded bushing in thread engagement with a threaded portion of said plunger.

16. An electrical terminal comprising a hollow post, a conductive plunger slidably disposed within said post,

said plunger having a portion extending outwardly through a slot in said post, said plunger including an L-shaped projection connected to said extending portion of said plunger, said L-shaped projection comprising a first member extending away from said post and a second member extending transverse to said first member in a direction generally parallel to said post at a position spaced outwardly of said post, further conductive means extending out wardly from said post at a fixed position generally parallel to and spaced from said first member wherein said extending portion, said L-shaped projection and said further conductive means define a substantially closed aperture disposed external of said post for receiving electrical conductors, the size of said aperture varying with variations in the spacing between said first member and said further conductive means, and means normally urging said plunger in a direction tending to bring said first member closely adjacent said further conductive means whereby said aperture has a minimum cross-sectional area.

References Cited UNITED STATES PATENTS 1,642,042 9/ 1927 Polk 339242 2,113,852 4/1938 Meade 339-249 3,001,173 9/1961 Swengel 339-253 3,104,926 9/1963 Scoville 339254 MARVIN A. CHAMPION, Primary Examiner.

P. TEITELBAUM, Assistant Examiner. 

1. AN ELECTRICAL TERMINAL COMPRISING A HOLLOW CONDUCTIVE POST HAVING AN ELONGATED SLOT IN A SURFACE THEREOF, A CONDUCTIVE PLUNGER SLIDABLY DISPOSED WITHIN SAID POST, SAID PLUNGER HAVING A PORTION EXTENDING OUTWARDLY THROUGH SAID SLOT, SAID PLUNGER INCLUDING AN L-SHAPED PROJECTION COMPRISING A FIRST MEMBER EXTENDING OUTWARDLY OF SAID POST FROM SAID EXTENDING PORTION OF SAID PLUNGER AND A SECOND MEMBER EXTENDING UPWARDLY FROM SAID FIRST MEMBER IN A DIRECTION GENERALLY PARALLEL TO SAID SLOT AT A POSITION SPACED OUTWARDLY OF SAID POST, FURTHER CONDUCTIVE PROJECTING MEANS EXTENDING OUTWARDLY FROM SAID POST AT A FIXED POSITION ABOVE SAID FIRST MEMBER AND EXTENDING TOWARD SAID SECOND MEMBER WHEREIN SAID EXENDING PORTION, SAID L-SHAPED PROJECTION AND SAID FURTHER PROJECTING MEANS DEFINE A VARIABLY SIZED APERTURE DISPOSED EXTERNAL OF SAID POST FOR RECEIVING ELECTRICAL CONDUCTORS, AND SPRING MEANS DISPOSED BETWEEN SAID POST AND SAID PLUNGER FOR NORMALLY URGING SAID PLUNGER IN A DIRECTION TENDING TO BRING SAID FIRST MEMBER CLOSELY ADJACENT SAID FURTHER PROJECTING MEANS WHEREBY SAID APERTURE HAS A MINIMUM CROSS-SECTIONAL AREA, SAID PLUNGER BEING MOVABLE WITHIN SAID POST AGAINST THE FORCE OF SAID SPRING FOR MOVING SAID L-SHAPED PROJECTION DOWNWARD RELATIVE TO SAID FURTHER PROJECTING MEANS THEREBY TO INCREASE THE CROSS-SECTIONAL AREA OF SAID APERTURE. 